
Mike, we have posts planted by the sides of the roads, so we can tell where the edge of the road is. Even when the snow is 3' deep, we have those for reference points.
Pete, the problem I see with adapting this method to water skis, is that the counter is limited to 15 mph. I water ski at about 30 mph. I would have to fashion a reduction system, to keep the counter from spinning too fast. But hey, I'm game. It works on X-C skis, so we should be able to adapt to water.